Fabrication of Nonbiofouling Surface and Its Application to Surface Plasmon Field-Enhanced Fluorescence Spectroscopy

Abstract

Reducing the non-specific binding of proteins on a chip surface is essential for the development of biosensors with high sensitivity and specificity. We fabricated poly(oligo(ethylene glycol) methacrylate) (pOEGMA) films with various thicknesses as a nonbiofouling surface for surface plasmon field-enhanced fluorescence spectroscopy (SPFS). To accomplish a sensitive SPF signal, the thickness of the pOEGMA films was controlled by surface-initiated atom transfer radical polymerization (SI-ATRP) on gold-coated glass (Au/Glass) and gold-coated Si (Au/Si) substrates. When fluorophores immobilized on the pOEGMA films were directly excited without a plasmon effect, the fluorescence intensity displayed a linear dependency on the tested thickness of the pOEGMA films on both Au/Si (9-60 nm) and Au/Glass (8-56 nm). As a result, the surface plasmon fieldinduced fluorescence intensity on Au/Glass enabled thickness-dependent sensitivity. The SPF signal on 50-nm-thick pOEGMA films was estimated to be 100 -fold stronger than that on 13-nm-thick pOEGMA films. Since the SPFS on pOEGMA film can allow an easy conjugation of biomolecules and provide a high resistance to biofouling events, our fabricated system has a great potential as a platform for biosensors with high sensitivity.